Stereoregular configuration and higher order structure of liquid crystalline polyacetylene derivatives

Stereoregular configuration and higher order structure of side-chain liquid crystalline (LC) polyacetylene derivatives recently developed were investigated through X-ray diffraction (XRD) measurements. XRD analyses indicated that all of the polymers showed layered structures in the LC states to exhibit smectic A phases, which is in agreement with the results of polarizing optical microscope. We also found that the LC side-chains are alternatively located at both sides of the polyene chain, giving rise to a stereoregular sequence such as head-head-tail-tail linkage. Possible mechanisms of polymerization for LC-substituted acetylene and subsequently occurring cis-trans isomerization are proposed.